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PRIMIS (Phase 3 Study of Cilofexor) News

Statement From Gilead Sciences on September 27, 2022

Early Termination of Gilead-Sponsored Study GS-US-428-4194:

A Phase 3, Randomized, Double-Blind, Placebo-Controlled Study Evaluating the Safety, Tolerability, and Efficacy of Cilofexor in Non-Cirrhotic Subjects with Primary Sclerosing Cholangitis (PSC) On Monday, September 26, 2022, Gilead announced to clinical investigators plans to discontinue the Phase 3 PRIMIS study (GS-US-428-4194) of cilofexor (GS-9674), an investigational FXR agonist, in adults with non-cirrhotic large-duct primary sclerosing cholangitis (PSC). This decision followed the review of data from a planned interim futility analysis. This analysis was based on the primary endpoint after the first 160 participants had completed Week 96 or Early Termination (ET) assessments in the Blinded Study Phase. The results indicated the futility criterion was met, triggering the data monitoring committee to recommend stopping PRIMIS study. An internal committee at Gilead, who is external to the PRIMIS study, evaluated the futility analysis and unblinded data, confirming the DMC’s recommendation.

The committee determined that there is no benefit to continuing the trial and exposing patients to the study drug or, certain procedures required for the study, such as liver biopsies. As such, the PRIMIS study is being terminated. Importantly, neither the DMC nor the internal unblinded Gilead committee identified any safety concerns associated with cilofexor.

We are disappointed by this outcome of cilofexor in PSC. We are deeply grateful to the investigators and their PSC patients for their contributions to the PRIMIS trial and to clinical research in PSC, a disease with great unmet need for safe and efficacious therapeutics. Inflammatory and fibrotic diseases are a key focus of our work to bring forward 10+ transformative therapies over the next decade, and we remain committed to developing treatments for patients with liver disease. Importantly, this decision does not affect our ongoing Phase 2 study (GS-US-454-6075) evaluating the safety and efficacy of semaglutide, and the fixed-dose combination of cilofexor and firsocostat, alone and in combination, in patients with compensated cirrhosis (F4) due to nonalcoholic steatohepatitis (NASH). This trial will continue without modification; we remain confident in cilofexor’s safety profile and its potential contribution to efficacy in NASH.


For more information, please contact Gilead Public Affairs at


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